Movable barriers, such as garage doors and the like, generally include a multi-panel door supported by a track system, upon which the door is movable between an open, horizontal position and a closed, vertical position. The door panels are pivotally secured to each other via hinges and movably secured to the track system via rollers.
Consumers have steadily indicated a desire for lighter weight, thermally efficient door panels, to reduce energy costs and noise while improving safety. Such door panels may be constructed using a front facer and a rear facer that define a volume therebetween. That volume may be filled with a foamed polymer material or the like. The foam adds structural integrity, adheres the panel components together, and improves the door's insulating properties. Such designs are lighter and in some cases less expensive than traditional solid wood or metal doors.
In some cases these foam filled panels are constructed using both a non-metal front facer and a non-metal rear facer. Such panels may be made in a continuous production process wherein a front facer having opposed longitudinal edges is continuously provided, a metal rail is continuously secured to each longitudinal edge, a foaming material is continuously applied on the front facer between the rails, a rear facer is continuously brought into contact with the rails, and the front facer, metal rails, rear facer and foaming material are drawn through a laminator which includes a plurality of rollers. This continuous production process is an improvement in many respects over the prior method, known as a batch process, in which one panel was formed at a time in a mould. The continuous production method is more efficient, less time consuming, and less expensive.
The production of laminated sectional door panels is complex, however, and results in various stresses in the final product as a result of the lamination processing heat, pressure and tension. As a result of these stresses, sectional door panels can become deformed or “bowed” during or after processing. The tendency to deform either during or after processing is highest when the door panel has one or both of its facers made of plastic. Elevated temperatures and pressures of the insulating foam at the time of lamination can cause the resulting sectional door panel to be unstable at ambient conditions. When the insulating foam cools it can shrink at a higher rate than the outer skins of the panel, causing the panel to deform. In addition, normal environmental thermal cycles in some climates can cause insulated sectional door panels to deform long after they have been produced.
Some sectional door panels are produced from blocks of cut foam rather than by a lamination process. These non-laminated insulated door panels do not experience the same processing conditions as laminated door panels, and therefore are not predisposed to deformation like the laminated panels. Nonetheless, these non-laminated door panels often are equipped with vertical reinforcements, known as stiles, which are used for hinge attachment but also serve to reinforce the panel. Although the stiles help to reinforce the door panels, they also significantly affect the appearance of the door panel because they are exposed to the inside of the door.
Thus, there exists a need in the art for a laminated door panel produced by a continuous lamination process having integral reinforcement to prevent deformation, without altering the appearance of the door panel.